The present invention relates to a control system for a split type air-conditioner wherein an indoor unit and an outdoor unit are installed separately from each other.
Split type air-conditioners comprising an indoor unit and an outdoor unit positioned separately from each other have been widely used. Such split type air-conditioners are provided with an indoor control circuit for effecting control of the indoor unit and an outdoor control circuit for effecting control of the outdoor unit. Accordingly, a signal conductor or line for coupling the two control circuits is required in order to serially transmit control logic signals therebetween.
Meanwhile, in the split type air-conditioners, when, for instance, heating operation is effected, there are instances where the outdoor unit enters into cooling operation cycle to effect defrosting operation, disregarding the control signals transmitted from the indoor unit. In this situation, it is impossible for the indoor unit to directly detect the entry of the outdoor unit into the defrosting operation. For this reason, temperature sensed by an indoor heat exchange sensor is monitored to indirectly detect the defrosting operation of the outdoor unit.
However, with such an indirect detection, it is difficult for the indoor unit to be fully informed of the state of the outdoor unit. Further, when a compressor is turned off in response to a command from the outdoor control circuit, it is also difficult to detect it at the indoor unit. Thus, the prior art control systems have drawbacks in that it is difficult for the indoor unit to detect control operation of the outdoor unit which is independently effected disregarding the control signals transmitted from the indoor unit. This causes inconveniences to users.